1. Field of the Invention
This invention relates generally to the field of manufacturing of semiconductor devices, and more specifically to a process to print fields on a wafer in a way that increases the semiconductor manufacturer (FAB) throughput, profitability and/or product reliability.
2. Background Art
The annual sales of the semiconductor industry are around $152,000,000,000 to $200,000,000,000 a year. New semiconductor manufacturing plants (FABs) cost from $2 billion to more than $10 billion. Large increases in fabrication cost are primarily driven by an increase in equipment costs. Algorithms that increase a FAB's productivity and/or profitability, even by a small percentage, will reduce the cost of a die and will significantly increases the profitability of the semiconductor company.
Today the following model is typically used to calculate the cost of a die:Cdie=Cwafer/(Ndies on a wafer*Ywafer) where:                Cdie is the cost of a die;        Cwafer is the cost to manufacture a wafer;        Ndies on a wafer is the number of dies on a wafer; and        Ywafer is the wafer yield.        
Prior approaches to laying out dies on a wafer typically assume uniform manufacturing cost for placing reticles on the wafer. The objective for the prior optimization algorithm is to reduce the manufacturing cost by reducing the number of reticle fields and increasing the number of gross dies. Furthermore, new process technologies require that fields be printed on a wafer, even if they will not produce any good-yielding dies. Prior art optimization techniques, for example, as disclosed in U.S. Pat. Nos. 5,874,189 and 6,016,391, will eliminate the reticle fields that do not produce good-yielding dies. However, by doing so they will reduce the yield of the dies placed on the wafer. Furthermore, the prior approaches assume uniformity of yield and product performance across the wafer and uniformity in the manufacturing cost. As a result, they may increase the number of dies placed on the wafer, but the total dies shipped to the customers will be reduced. Using the prior approaches will thus cause loss in yield, product reliability, FAB throughput and FAB profitability.